text: Properly designed copper roofs minimize movements due to thermal changes. Coppers low thermal expansion, 40% less than zinc and lead, helps to prevent deterioration and failure. Also, coppers high melting point ensures that it will not creep or stretch as some other metals do.
  On small gable roofs, thermal movement is relatively minor and usually is not an issue. On wide-span buildings over  and when long panels are used, an allowance for thermal expansion may be necessary. This enables the roof to "float" over supporting substructures while remaining secure.